ACHIEVING AN OPTIMAL BALANCE OF PROPERTIES IN 40KHMFA STEEL USING A MULTIFRACTAL APPROACH
ДОСЯГНЕННЯ ОПТИМАЛЬНОГО БАЛАНСУ ВЛАСТИВОСТЕЙ СТАЛІ 40ХМФА МУЛЬТИФРАКТАЛЬНИМ ПІДХОДОМ D.B. Hlushkova1
Volchuk V.M. Ragulin V.M. Kanibekova M.A.
2026National Science Center, Kharkov Institute of Physics and Technology
Problems of Atomic Science and Technology
2026#2026Issue 1140 - 145 pp.
The resistance of 40KhMFA steel to sulfide stress cracking (SSC) was investigated for the production of dual-purpose pipes with enhanced strength and corrosion resistance through optimization of heat treatment regimes. The effect of quenching followed by long-term tempering (from 660 to 740 °C in 20 °C increments) for 5, 30, 60, and 90 min on changes in mechanical properties was studied. Structural evaluation after heat treatment was performed using multifractal analysis. Multifractal parameters (D0, Δ, K, Δf) effectively describe structural transformations in terms of heterogeneity, self-similarity, and ordering of the acicular bainitic-martensitic structure, correlating with properties: a decrease in D0 increases ductility, while increases in Δ and K contribute to higher strength. With increasing tempering duration, acicular morphology is retained, but carbide coarsening occurs. Regression models with high R² values were developed, enabling the prediction of mechanical properties based on multifractal characteristics. The results confirm the superiority of the multifractal approach over traditional quantitative metallographic methods for non-destructive monitoring of structural degradation (corrosion, fatigue) and optimization of heat treatment. The proposed approach will enable the integration of digital systems for predicting the service life of pipes and structural elements in nuclear power engineering. Based on the need to ensure a high level of mechanical properties, the recommended tempering regime for 40KhMFA pipe steel is (700 ± 10) °C with a holding time of 90 min.
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Kharkiv National Automobile and Highway University, Kharkiv, Ukraine
Prydnіprovska State Academy of Civil Engineering and Architecture, Dnipro, Ukraine
Kazakh Automobile and Road Institute named after L.B. Goncharov, Almaty, Kazakhstan
Kharkiv National Automobile and Highway University
Prydnіprovska State Academy of Civil Engineering and Architecture
Kazakh Automobile and Road Institute named after L.B. Goncharov
10 лет помогаем публиковать статьи Международный издатель
Книга Публикация научной статьи Волощук 2026 Book Publication of a scientific article 2026